How to adjust button size to fit the text in Delphi FireMonkey?

Question

I want button size (width and height) to be as small as possible, but I want it to fit the text. Any code example? Delphi XE4 FireMonkey Mobile Application.

Answer 1

FireMonkey renders text via methods using TTextLayout class.
We can access this methods via a class helper and then change the buttons size based on the information provided by the layout.

uses FMX.TextLayout;

type
  TextHelper = class helper for TText
     function getLayout : TTextLayout;
  end;

function TextHelper.getLayout;
begin
  result := Self.fLayout;
end;

procedure ButtonAutoSize(Button : TButton);
var
  bCaption : TText;
  m : TBounds;
begin
  bCaption := TText(Button.FindStyleResource('text',false));
  bCaption.HorzTextAlign := TTextAlign.taLeading;
  bCaption.VertTextAlign := TTextAlign.taLeading;
  m := bCaption.Margins;
  Button.Width  := bCaption.getLayout.Width  + m.Left + m.Right;
  Button.Height := bCaption.getLayout.Height + m.Top  + m.Bottom;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
   ButtonAutoSize(Sender as TButton);
end;

---

Update

Here is a more future proof solution that doesn't require exposing private class fields.

uses FMX.Objects;

procedure ButtonAutoSizeEx(Button: TButton);
var
  Bitmap: TBitmap;
  Margins: TBounds;
  Width, Height: Single;
begin
  Bitmap := TBitmap.Create;
  Bitmap.Canvas.Font.Assign(Button.TextSettings.Font);
  Width := Bitmap.Canvas.TextWidth(Button.Text);
  Height := Bitmap.Canvas.TextHeight(Button.Text);
  Margins := (Button.FindStyleResource('text', false) as TText).Margins;
  Button.TextSettings.HorzAlign := TTextAlign.Leading;
  Button.Width := Width + Margins.Left + Margins.Right;
  Button.Height := Height + Margins.Top + Margins.Bottom;
end;

This example omits any word wrapping or character trimming.

Answer 2

Based on the answer of @Peter, but no need to create a bitmap:

//...

type
    TButtonHelper = class helper for TButton
        procedure FitToText(AOnlyWidth: Boolean = False);
    end;

implementation

//...

// Adapt button size to text.
// This code does not account for word wrapping or character trimming.
procedure TButtonHelper.FitToText(AOnlyWidth: Boolean = False);
var
    Margins: TBounds;
    TextWidth, TextHeight: Single;
    Obj: TFmxObject;
const
    CLONE_NO = False;
begin
    Obj := FindStyleResource('text', CLONE_NO);
    if Obj is TText then    //from Stackoverflow comments: Some time FindStyleResource returns nil making the app crash
    begin
        Margins := (Obj as TText).Margins;
        TextWidth := Canvas.TextWidth(Text);
        if not AOnlyWidth then
          TextHeight := Canvas.TextHeight(Text);
        TextSettings.HorzAlign := TTextAlign.taLeading;    //works in XE4
        //later FMX-Versions ?: TextSettings.HorzAlign := TTextAlign.Leading;
        Width := TextWidth + Margins.Left + Margins.Right;
        if not AOnlyWidth then
          Height := TextHeight + Margins.Top + Margins.Bottom;
    end;
end;